Advances in laser source technology and in optical recording systems have brought about a great demand for a reliable optical recording media which is suitable as a data storage device. To be suitable as a data storage device, the optical recording media should have high sensitivity to a laser for recording data; good signal to noise ratio on play back; no degradation on repeated paay back; durability under normal operating conditions; a resolution of one micron or better; a low bit error rate; and manufacturability at low cost.
One known material which has been proposed as an optical recording media is tellurium. Although tellurium films have adequate sensitivity to a laser for recording data, these films degrade rapidly under normal operating conditions. For example, an unprotected tellurium film with a nominal thickness of 300 .ANG. will oxidize in air in a matter of days, rendering the material completely useless.
In order to prolong the life of tellurium films, alloys of tellurium have been developed. However, it has been found that these tellurium alloys are not sufficiently sensitive to laser recording. Tellurium films have also been enclosed in an inert gas sandwich in order to increase its durability. However, the cost of making an optical recording disc from the sandwiched tellurium is prohibitively expensive.
For increased recording sensitivity, a tri-layer film consisting of a metal reflector, a dielectric spacer and a thin tellurium film, on the order of 50-100 .ANG., has also been proposed. Because the tellurium film is so thin, however, the durability of this tri-layer media is even worse than the single layer tellurium media.